Here's a third vote for spending your money on something else. That sail is too small to need a sock, and the relative weight of the apparatus would be too much for a rig that small.
Treat yourself to some free-running hardware, or a back up GPS....
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"